[log in to unmask] (mailto:[log in to unmask]) writes:
would imagine that trying to breed resistance to imidacloprid is futile
(even if it was a factor in CCD, do bees vary for susceptibility?) whereas
breeding resistance to Nosema ceranae and viruses is almost guaranteed to work.
Bees do indeed vary in susceptibility to pesticides of all types. That's
the reason why the original label testing guidelines hammered out in the U.S.
in the 60s, early 70s insisted on using at least three colonies for any
testing aimed at protection of pollinators from the toxic effects of pesticides - a
practice that has been more or less forgotten by some of the private labs
conducting testing for chemical companies, and often overlooked by EPA. Some
of these companies use ONE colony, sub-sample it, which is NOT true
replication of populations. If that ONE colony is particularly susceptible, beekeepers
win. If that colony is resistant, the dose that kills may be
under-estimated.
However, resistance to pesticides generally is reflected in differences in
the dose needed to harm - e.g., how much is needed to kill 50% of the bees
over an established period of time - 24, 48, 96 hours?
A poison is a poison, many directly affecting the insect's nervous system,
other basic functioning. There may be differences in susceptibility relative
to dose, but bees are not likely to ever become truly resistant to any toxic
chemical.
Simply stated, if something chomps your head off, perforates your gut, is
poisonous, you're not going to develop resistance.
Bees may be bred for resistance to a variety of pathogens - although again,
it will depend somewhat on the nature of the pathogen, how it injures the
bee. With mites, one can readily see races of bees that seem to better tolerate
them, maybe even see behaviors such as hygienic traits that affect the
resistance.
With N. ceranae - not sure that we've found any resistance traits, but time
will tell. We're certainly looking for colonies that seem to tolerate this
pathogen - and we've found a couple that have lasted for more than a year with
heavy infestations - so it looks like there may be resistant colonies that
could be bred from. Haven't a clue as to WHY these are resistant.
With viruses, lots of ways that resistance to any one virus might occur.
And, if its economically feasible to detect viruses, you may be able to cull the
worst ones out - just as you do for AFB.
Jerry
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